NCERT Solutions For Class 12 Vistas English The Enemy

NCERT Solutions For Class 12 Vistas English The Enemy

QUESTIONS FROM TEXTBOOK SOLVED

READ AND FIND OUT
Q1. Who was Dr Sadao? Where was his house?
Ans. Dr Sadao Hoki was an eminent Japanese surgeon and scientist. He had spent eight valuable years of his youth in America to learn all that could be learnt of surgery and medicine there. He was perfecting a discovery which would render wounds entirely clean.
Dr Sadao’s house was built on rocks well above a narrow beach that was outlined with bent pines. It was on a spot of the Japanese coast.

Q2. Will Dr Sadao be arrested on the charge of harbouring an enemy?
Ans. Dr Sadao knew that they would be arrested if they sheltered a white man in their house. The wounded man was a prisoner of war who had escaped with a bullet on his back. Since Japan was at war with America, harbouring an enemy meant being a traitor to Japan. Dr Sadao could be arrested if anyone complained against him and accused him of harbouring an enemy.

Q3. Will Hana help the wounded man and wash him herself?
Ans. The gardener and the cook were frightened that their master was going to heal the wound of a white man—an enemy. They felt that after being cured he (the white man) will take revenge on the Japanese. Yumi, the maid, was also frightened. She refused to wash the white man. Hana rebuked the maid who had refused to wash a wounded helpless man. Then she dipped a small dean towel into the steaming hot water and washed the white man’s face. She kept on washing him until his upper body was quite dean. But she dared not turn him over.

Q4. What will Dr Sadao and his wife do with the man?
Ans. Dr Sadao and his wife, Hana, had told the servants that they only wanted to bring the man to his senses so that they could turn him over as a prisoner. They knew that the best possible course under the circumstances was to put him back into the sea. However, Dr Sadao was against handing over a wounded man to the police. He dedded to carry him into his house. He operated upon him and extracted the bullet from his body. He kept the white man in his house. He and his wife looked after him and fed him till he was strong enough to walk on his legs. .

Q5. Will Dr Sadao be arrested on the charge of harbouring an enemy?
Ans. It was the seventh day since Dr Sadao had operated upon the young white man. Early that morning, their three servants left together. In the afternoon, a messenger came there in official uniform. He told Dr Sadao that he had to come to the palace at once as the old General was in pain again.
Hana, who had thought that the officer had come to arrest Dr Sadao, asked the messenger, “Is that all?” The baffled messenger enquired if that was not enough. She tried to cover her mistake by expressing regret and admitted that the General’s illness was enough. Dr Sadao told the General about the white man he had operated upon. Since Dr Sadao was indispensable to the General, he promised that Dr Sadao would not be arrested.

Q6. What will Dr Sadao do to get rid of the man?
Ans.Dr Sadao had told the old General that he had operated upon a white man. The General promised to send his private assassins to kill the man silently and secretly at night and remove his body. Dr Sadao left the outer partition of white man’s room open. He waited anxiously for three nights. The servants had left their house. His wife Hana had to cook, clean the house and serve the wounded man. She was unaccustomed to this labour. She was anxious that they should get rid of the man.
Dr Sadao told Tom, the white man, that he was quite well then. He offered to put his boat on the shore that night. It would have food and extra clothing in it. Tom might be able to row to the little island which was not far from the coast. It had not been fortified. The .water was quite deep. Nobody lived there, as it was submerged in storm. Since it was not the season of storm, he could live there till he saw a Korean fishing boat pass by. He gave the man his flashlight. He was to signal twice with his flashlight at sunset in case his food ran out. In case, he was still there and all right, he was to signal only once.
Dr Sadao gave the man Japanese clothes and covered his blond head with a black doth. In short, Dr Sadao helped the man to escape from Japan. At the same time he also got rid of the man.

READING WITH INSIGHT
Q1.There are moments in life when we have to make hard choices between our roles as private individuals and as citizens with a sense of national loyalty? Discuss with reference to the story you have just read.
Ans. Dr Sadao Hoki faces a dilemma when he finds the body of an unconscious wounded white man lying on the lonely coast with dangerous rocks near his house. His first reaction was that the person was perhaps a fisherman who had been washed from his boat. He ran quickly down the steps. His wife, Hana came behind him. When they came near, Sadao found that the man was wounded and lay motionless. His face was in the sand. As they saw his face, they found that he was a white man with long yellow hair and a rough yellow beard.
Being an expert surgeon, Dr Sadao saw that the man had a gun-wound on the right side of his lower back. He at once packed the wound with sea moss to stanch the fearful bleeding. Since Japan was at war with America, the white man was an enemy. Dr Sadao muttered, “What shall we do with this man?” He answered the question himself, “The best thing that we could do would be to put him back in the sea.” His wife approved of his decision.
Then Sadao made another observation. If they sheltered a white man in their house they would be arrested and if they turned him over as a prisoner, he would certainly die. Hana still insisted on putting him back into the sea. From his battered cap, Dr Sadao concluded that he was a sailor from an American warship. The man was a prisoner of war. He had escaped and that was why he was wounded in the back..
Hana asked if they were able to put him back into the sea. Sadao then said that if the man was whole he could turn the man over to the police without difficulty. He cared nothing for the man. He was their enemy. All Americans were their ‘enemy’. But since he was wounded… Hana understood his dilemma and realised that in the conflict between his sense of national loyalty and his duty as a doctor, it was the latter which proved dominant. Since Sadao too could not throw him back to the sea, the only course left for them was to carry him to their house. Sadao enquired about the reaction of the servants.
Hana said that they would, tell the servants that they intended to give the man to the police. She told Sadao that they must do so. They had to think of the children and the doctor’s position. It would endanger all of them if they did not give that man over as a prisoner of war.
Sadao agreed and promised that he would not think of doing anything else.

Q2. Dr Sadao was compelled by his duty as a doctor to help the enemy soldier. What made Hana, his wife, sympathetic to him in the face of open defiance from the domestic staff?
Ans. Dr Sadao and his wife, Hana, together lifted the wounded man and carried him to an empty bedroom in their house. The man was very dirty. Sadao suggested that he had better be washed. He offered to do so if she would fetch water. Hana was against it. She suggested that the maid, Yumi, could wash the man. They would have to tell the servants. Dr Sadao examined the man again and remarked that the man would die unless he was operated upon at once. He left the room to bring his surgical instruments.
The servants did not approve of their master’s decision to heal the wound of a white man. Even Yumi refused to wash the white man. There was so fierce a look of resistance upon Yumi’s round dull face that Hana felt unreasonably afraid. Then she said with dignity that they only wanted to bring him to his senses so that they would turn him over as a prisoner. However, Yumi refused to have anything to do with him. Hana asked Yumi gently to return to her work.
The open defiance from the domestic staff hurt Hana’s feelings. She had told the servants to do what their master commanded them. She was convinced of her own superiority. She now became sympathetic to her husband and helped him in his efforts to heal the wounded man. Though the sight of the white man was repulsive to her, she washed his face and his upper body. She prepared herself to give him the anaesthetic according to her husband’s instructions. She had never seen an operation. She choked and her face turned pale like sulphur. She felt like vomiting and left for a while. She returned after retching and administered anaesthetic to the man. Thus she co-operated with her husband fully to save the wounded man.

Q3. How would you explain the reluctance of the soldier to leave the shelter of the doctor’s home even when he knew he couldn’t stay there without risk to the doctor and himself?
Ans. On the third day after the operation, the young man asked Dr Sadao what he was going to do with him and if he was going to hand him over. Dr Sadao said that he did not know himself what he would do with the mem. He ought to hand him over to the police as he was a prisoner of war.
The young man saw that Dr Sadao and his wife Hana were different from other Japanese. They spoke English well, looked after him and served him food. Seven days after the operation of the man, Dr Sadao was called to the palace to see the General. Hana thought that the police had come to arrest Dr Sadao. Dr Sadao confided in the General and he (General) promised to send his personal assassins to kill the man and remove his body. Dr Sadao waited for three nights. Nothing happened. Then he made a plan to let the prisoner escape. He told Tom, the young American, about it. The young man stared at him and asked if he had to leave. It seemed he was reluctant to leave. Dr Sadao told him that he should understand everything clearly. It was not hidden that he was there and this situation was full of risk for himself as well as for the doctor and his family. Thus it is quite clear that the reluctance of the soldier was caused by the single motive of self-preservation. He knew from the treatment he had received from the couple that they would save him.

Q4. What explains the attitude of the General in the matter of the enemy soldier? Was it human consideration, lack of national loyalty, dereliction of duty or simply self-absorption?
Ans. During his meeting with the General, Dr Sadao told him about the man he had operated on successfully. He explained that he cared nothing for the man. The General appreciated his skill and efficiency and promised that he would not be arrested.
The General thought it quite unfortunate that the man had been washed up to Dr Sadao’s doorstep and thought it best if he could be quietly killed. He promised to send his private assassins to do so and remove his dead body. He suggested that Dr Sadao should leave the outer partition of the white man’s room to the garden open at night.
It is evident that the General had no human consideration in this matter. For him an enemy was an enemy and must be wiped out. He wanted the man to be eliminated silently to save the doctor from being arrested. It was neither lack of national loyalty nor dereliction of duty that guided and inspired his decision. It was simply his sense of self-absorption. He “wanted to keep Dr Sadao safe only for his own sake. He had no faith in the other Germany trained doctors. He might have to be operated upon anytime when he had another attack and he had full faith in the skill and loyalty of Dr Sadao only.
This fact is further corroborated by the General’s remarks to Dr Sadao, one week after the emergency operation upon the General. Dr Sadao informed him that the man had escaped. The General asked whether he had not promised Sadao that he would kill the
man for him. Dr Sadao replied that he had done nothing. The General admitted that he had forgotten his promise as he had been suffering a great deal and he thought of nothing but himself. He revealed the whole truth. He admitted that it was careless of him to have forgotten his promise. But added that it was not lack of patriotism or dereliction of duty on his part.

Q5. While hatred against a member of the enemy race is justifiable, especially during wartime, what makes a human being rise above narrow prejudices?
Ans. It is the consciousness of the demands of one’s calling that make a sensitive soul respond to the call of his duty as a professional doctor to attend to the wounded human being regardless of his being an enemy.
In the story ‘The Enemy’ Dr Sadao Hoki finds a prisoner of war washed ashore and in a dying state thrown to his doorstep. As a patriot, it is his duty to hand him over to the police. If he does not want to be entangled, the next best thing is to put him back to the sea.
However, the surgeon in him instinctively inspires him to operate upon the dying man and save him from the jaws of death. First, he packs the wound with sea-moss to stanch the fearful bleeding. Then he brings him home with the help of his wife. In spite of stiff opposition and open defiance of the servants, he operates upon the man and harbours him till he is able to leave. He knows fully well the risk of sheltering a white man—a prisoner of war—in his house. But his sentimentality for the suffering and wounded person help him rise above narrow national prejudices and extend his help and services even to an enemy.

Q6. Do you think the doctor’s final solution to the problem was the best possible one in the circumstances?
Ans. Yes, I think the doctor’s final solution to the problem was the best possible one in the circumstances. Initially, the doctor as well as his wife thought that the best as well as kindest thing would be to put him back into the sea. But neither of them was able to put him back into the sea.
Sadao explained that if the man was whole he could turn him over to the police without difficulty, but since he was wounded, the doctor could not throw him back to the sea. He could not kill the man whom he had saved from the jaws of death.
The General promised to send his private assassins to kill the man and remove his dead body. Sadao waited for three nights for their arrival, but they never came as the General being preoccupied with his own suffering, forgot everything else.
Meanwhile the fear of Hana, the doctor’s wife, that he would be arrested on the charge of harbouring an enemy kept on mounting. Dr Sadao made up his mind to get rid of the man as it was not only inconvenient but also dangerous for them to have him there any longer. He, therefore, quietly devised the plan of letting the prisoner escape by using his own boat and Japanese clothes.
As soon as the enemy left, the servants returned and life became normal once again. Dr Sadao informed the General that “the man” had escaped. The General admitted that he had forgotten his promise as he thought of nothing but himself as he was suffering a great deal. He confessed that it was careless of him but it was not his lack of patriotism or dereliction of duty. In short, the doctor’s strategy to let the prisoner escape was the best possible solution to the problem under the prevailing circumstances.

Q7. Does the story remind you of ‘Birth’ by A. J. Cronin that you read in ‘Snapshots’ last year? What are the similarities?
Ans. Yes, the story ‘The Enemy’ by Pearl S. Buck certainly reminds us of the story ‘Birth’ by A. J. Cronin. Both the stories have certain obvious similarities. Both the stories revolve around the protagonist who is a doctor. Both of them focus on the doctor’s devotion and dedication to his duty and his concern for the well-being of his patient. The doctor sacrifices his own rest and comfort while attending to the patient. If the doctor brings a ‘still-born’ baby back to life in the story ‘Birth’, Dr Sadao Hoki performs no less a miracle. He saves an almost dying man from the jaws of death by skilfully extracting the bullet from his body and giving him medicines and injections for quick relief.
Dr Sadao runs a greater risk than Dr Andrew Mason. While the former could be arrested on the charge of harbouring an enemy and condemned to death, the latter (Dr Andrew) was foregoing rest and staking his reputation as a medical practitioner. He had had a disappointing evening with Christine, the girl he loves, but he forgets his personal feelings and concentrates on the safe delivery of child and then of reviving the middle-aged mother and the still-born child. Similarly, Dr Sadao is dedicated to his patient and his problems. He forgets everything while concentrating on the operation. His servants have defied him for sheltering an enemy and run away. His wife, Hana, has to do menial jobs while attending to the patient and her retching disturbs him. Her distress and his inability to attend to her make him impatient and irritable, but he does not desert the man who is under his knife. To conclude, we may say that the zeal, dedication and efforts of both the doctors are similar. There is difference of degree in the risk factor, but their devotion to suffering humanity is undoubtedly of the same kind.

Q8. Is there any film you have seen or novel you have read with a similar theme?
Ans. I remember an old Hindi film ‘Dr Kotnis ki Amar Kahani’ that deals with a similar theme. The eminent doctor gives up his practice and goes to the war front to look after the wounded and ailing soldiers and render them medical help. He spares no pain in performing his duties. He ignores the demands of his own body that is sleep, rest and comfort. Service to suffering humanity is his sole motivation and in his zeal to restore the maximum number of victims back to health, the doctor suffers from physical and mental exhaustion and ultimately dies.
The film based on the life of Florence Nightingale, the lady with the lamp, also glorifies the spirit of service and sacrifice of a member of the medical profession. It is through her sheer hard work and dedication to duty that Florence Nightingale raises the job of a nurse to a high pedestal.

MORE QUESTIONS SOLVED

SHORT ANSWER TYPE QUESTIONS
Q1.What do you learn about Sadao’s father from the story ‘The Enemy’?
Ans. Sadao’s father was a visionary. He knew that the islands near the sea coast were the stepping stones to the future for Japan. No one could limit their future as it depended on what they made it. His son’s education was his chief concern. He sent his son to America at the age of twenty-two to learn all that could be learned of surgery and medicine. He loved the Japanese race, customs and manners.

Q2. Why was Dr Sadao being kept in Japan and not sent abroad with the troops?
Ans. Sadao was an eminent surgeon and a scientist. He was perfecting a discovery which would render wounds entirely clean. Secondly, the old General was being treated medically for a condition for which he might need an operation. Due to these two reasons Sadao was being kept in Japan and not sent abroad with the troops.

Q3. Who was Sadao’s wife? Where had he met her? Why did he wait to fall in love with her?
Ans. Hana was Sadao’s wife. He had met her by chance at an American professor’s house. Professor Harley and his wife had been kind people. They held a party at their home for their few foreign students. Hana was a new student. He waited to fall in love with her until he was sure she was Japanese. It was because his father would never have received her unless she had been pure in her race.

Q4. When and where did Sadao marry Hana? How was their married life?
Ans. Sadao married Hana when they returned to Japan after finishing their work at medical school. Sadao’s father saw her. The marriage was then arranged in the old Japanese way. They had been married years enough to have two children. Their married life was quite happy. They still loved each other.

Q5. ‘Both of them saw something black came out of the mists’. What did they see and how did they react to it?
Ans. It was a man who had been flung up out of the ocean, to his feet by a breaker. He staggered a few steps with his arms above his head. Then the curled mists hid him again. When they next saw him, he was on his hands and knees crawling. Then they saw him fall on his face and lie there. Sadao thought that he was perhaps a fisherman who had been washed from his boat. He ran quickly down the steps. Hana followed him.

Q6. In which state did Sadao and Hana find the man? What did they learn about him?
Ans. The man lay motionless with his face in the sand. As they turned the man’s head, they saw that he was a white man with long yellow hair. His young face had a rough yellow beard. He was unconscious. From his battered cap they learnt that he was a sailor from an American warship.

Q7. What did Sadao learn about the white man’s wound?
Ans. Sadao saw that a gun-wound had been reopened on the right side of his lower back. The flesh was blackened with powder. The man had been shot recently and had not been tended. It was bad chance that the rock had struck the wound and reopened it.

Q8. How can you say that Sadao’s head and hands worked in different directions?
Ans. Sadao’s head told him to put the man back into the sea as he was an American soldier-an enemy of Japan. His trained hands seemed, of their own will, to be doing what they could to stanch the fearful bleeding. He packed the wound with the sea-moss that strewed the beach. The bleeding was stopped for the moment.

Q9.What dilemma did Sadao face about the young white man?
Ans. The white man was wounded. He needed immediate medical care. Dr Sadao could do so. But if they sheltered a white man in their house, they would be arrested. On the other hand, if they turned him over as a prisoner, he would certainly die. Dr Sadao was in a fix. It was difficult for him to come to any decision.

Q10.What was the attitude of Sadao and Hana towards the white man?
Ans. They stared upon the inert figure of the white man with a curious repulsion. Both talked of putting him back into the sea, but neither of them was able to do so alone. They hesitated. Sadao said that being American, the man was his enemy. He would have handed him over to the police if he had not been wounded. But since he was wounded… He left the sentence incomplete, implying that he couldn’t do so.

Q11.What solution did Hana offer to resolve Sadao’s predicament?
Ans. Hana found that neither of them could throw the white man back into the sea. There was only one thing to do. They must carry the man into their house. They must tell the servants that they intended to hand him over to the police. She reminded her husband of his position and children. It would endanger all of them if they did not give that man over as a prisoner of war.

Q12. How did Sadao and Hana take the man inside their house?
Ans. Together they lifted the man. He was very light. His arms were hanging down. They carried him up the steps and into the side door of the house. This door opened into a passage. Down the passage, they carried him towards an empty bedroom. They laid the man on the deeply matted floor.

Q13. Hana took out a soft quilt from the wall cupboard. Then she hesitated. Why? What did her husband suggest? Why did she not agree?
Ans. The quilt was covered with flowered silk and the lining was pure white silk. Secondly, the man was quite dirty. So Hana hesitated. Her husband suggested that he should be washed. He offered to wash him, if she was willing to fetch water. She could not bear for him to touch the man and offered to tell Yumi, the maid, to wash him.

Q14. Why did Dr Sadao had to touch the man? What did he observe?
Ans. The utter pallor of the man’s unconscious face moved Dr Sadao first to stoop and feel his pulse. It was faint but it was there. Then he put his hand against the man’s cold breast. The heart too was yet alive. He observed that the man would die unless he was operated on.

Q15. Why did Hana come behind Sadao when he went out of the room quickly?
Ans. Hana did not wish to be left alone with the white man. He was the first she had seen since she left America. He seemed to have nothing to do with those whom she had known there. Here he was her enemy, a menace, living or dead.

Q16. How did the servants react when their master told them about the wounded white man?
Ans. The servants were frightened and puzzled. The old gardener told Hana that the master ought not to heal the wound of that white man. He said that the white man ought to die. First he was shot. Then the sea caught him and wounded him with her rocks. If the master healed what the gun and the sea had done, they would take revenge on them.

Q17. Why had Hana to wash the wounded man herself?
Ans. Hana told Yumi to fetch hot water and bring it to the room where the white man was. Yumi put down the wooden bucket, but refused to wash the dirty white man. Hana cried at her severely. She told her to do what her master commanded her to do. The fierce look of resistance upon Yumfe dull face made Hana afraid. Under these circumstances, Hana had no option but to wash the white man herself.

Q18. How did Hana wash the wounded man?
Ans. First, Hana untied the knotted rugs that kept the white man covered. When she had his breast bare, she dipped a small clean towel into the steaming hot water and washed his face carefully. She kept on washing him until his upper body was quite clean. But she dared not turn him over for fear of the wound.

Q19. What help did Dr Sadao seek from Hana while operating the wounded white man?
Ans. First, he asked her to fetch towels. Then he told her that she would have to give him the anaesthetic if he needed it. Since, Hana had never done so, he told her that it was easy enough. He asked her to soak the cotton with anaesthetic and hold it near his nostrils. When he breathed badly, she had to move it away a little. Thus, Hana proved herself helpful to her husband.

Q20. How did Hana react to Sadao’s absorption in his work?
Ans. Sadao went on with his swift concise movements. He did not seem to hear her. She was used to his absorption when he was at work. She wondered for a moment if it mattered to him what the body was upon which he worked so long as it was for the work which he did so excellently.

Q21. What did Sadao remark when he peered into the wound with his bright surgeon’s light?
Ans. He remarked that the bullet was still there. He said so with cool interest. He then wondered
how deep that wound was. If it was not very deep it was possible that he could get the bullet. He observed that the bleeding was not superficial. The man had already lost much blood.

Q22. What made a cool surgeon (like Dr Sadao) speak sharply to his wife? How did she react to his command?
Ans. The sight of blood made Hana choke. Her face turned pale. She had never seen an operation. Dr Sadao spoke sharply and asked her not to faint. He did not put down his exploring instrument. He argued that if he stopped then the man would surely die. Hana clapped her hands to her mouth, leaped up and ran out of the room. He heard her retching in the garden. But he went on with his work.

Q23. What forced Dr Sadao to be impatient and irritable with his patient?
Ans. Sadao heard Hana retching in the garden and said that it would be better for her to empty her stomach. He went on with his work. He had forgotten that she had never seen an operation. But her distress and his inability to go to her at once made him impatient and irritable with the man who lay like dead under his knife.

Q24. What instructions did Sadao give to Hana to administer the anaesthetic and when?
Ans. The man was beginning to stir. Hana asked Sadao where the anaesthetic was. Sadao motioned with his chin. She now had the bottle and some cotton in her hand. Sadao instructed her to saturate the cotton with anaesthetic and hold it near the man’s nostrils. She had to move it away a little when he breathed badly.

Q25. How did Hana react to the stories they heard of the sufferings of the prisoners of war? What made her think so?
Ans. These stories came like flickers of rumour, told by word of mouth. They were always contradicted. Hana wondered whether these stories were true. In the newspapers the reports were that people received the Japanese armies gladly with cries of joy at their liberation.

Q26. In what context does Hana remember General Takima? What does she infer?
Ans. General Takima was a ruthless despot. At home he beat his wife cruelly. No one mentioned it now because he had won a victory in a battle in Manchuria. Hana remembers him in the context of the sufferings of the prisoners of war. She infers that if a man (like General Takima) could be so cruel to a woman in his power, he would be quite cruel to a prisoner. The deep red scars on the white man’s neck confirmed her apprehension.

Q27. “Ml thought left him. He felt only the purest pleasure.” Why, do you think, did Dr Sadao behave in this way?
Ans. Dr Sadao was concentrating hard on locating the bullet. He felt the tip of his probing instrument strike against something hard, dangerously near the kidney. He was filled with the purest pleasure at the success of his skill. He thought only of curing his patient and did not answer even his wife’s query.

Q28. Dr Sadao was ‘familiar with every atom of this human body’. Who had seen to that knowl¬edge and how?
Ans. It was Sadao’s old American professor of Anatomy who had seen to the perfect knowledge of human body. He would tell his students, ‘Ignorance of the human body is the surgeon’s cardinal sin.” He would go a step further and impress upon the budding surgeons to have as complete knowledge of the body as if they had made it. To operate with anything less than that meant a murder.

Q29. Comment on Dr Sadao’s attitude to the white man in the light of the following:
(i) “Sadao took up his wrist, hating the touch of it.”
(ii) “But certainly I do not want this man to live.”
(iii) “This man will live in spite of all.”
Ans. Sadao has an ambivalent attitude towards the wounded white man. Since he is their enemy, he hates touching his wrist. As a patriot he does not want that man to live. However, as a surgeon, he does not want the man to die after a successful operation. Hence, in order to revive his faint, feeble pulse, he gives him an injection. The pulse now flutters and then grows stronger. The survival of the man is the victory of the surgeon’s skill.

Q30. How did Harm look after the white man? How did he react?
Ans. Hana had to serve him herself, for none of the servants would enter the room. She did not like him and yet she was moved to comfort him. She found the man quite weak and terrified. She knelt and fed him gently from the porcelain spoon. He ate unwillingly but still he ate.

Q31. How did Dr Sadao respond to the boy’s query: “What are you going to do with me?…Are you going to hand me over?”
Ans. Dr Sadao examined the boy and then told him that he did not know himself what he would do with the boy. He ought to give him to the police as he was a prisoner of war.

Q32. What did Hana inform Sadao about the servants? How did Sadao react to it?
Ans. The servants felt that they could not stay there if their master sheltered the white man there any more. They also accused them of liking Americans and of having forgotten to think of their own country first. Dr Sadao protested that it was not true. Americans were their enemies. But he had been trained not to let a man die if he could help him. Hana told him that the servants could not understand it.

Q33. ‘Somehow the household dragged on’. How did the servants behave after Sadao had operated upon the American? What opinions did they express?
Ans. The servants grew more watchful day by day. Their courtesy was as careful as ever, but their eyes were cold towards Hana and Sadao. The old gardener was sore, why Sadao had not let the young man bleed when he was so near the death. The cook remarked contemptuously that being proud of his skill to save life that he saves any life. Yumi added that they must think of the children. She enquired: “What will be their fate if their father is condemned as a traitor?”

Q34. What two things happened on the seventh day after that?
Ans. In the morning the servants left together with their belongings tied in large square cotton kerchiefs. Hana paid them off gracefully and thanked them for all that they had done for her. In the afternoon, a messenger came to the door in official uniform.

Q35. How did Hana react when she saw a messenger at the door in official uniform?
Ans. Hana was working hard on unaccustomed labour. When she saw the uniformed messenger, her hands went weak and she could not draw her breath. She feared that the servants must have told everything already. She thought that they had come to arrest Dr Sadao.

Q36. Why, do you think, had the messenger come to Dr Sadao’s house? How did Hana react to the message and what did the messenger take exception to?
Ans. The messenger had arrived there to ask Dr Sadao to come to the palace as the old General was in pain again. In her anxiety for her husband’s safety, Hana asked if that was all. The messenger took exception to the word ‘all’ and enquired if that was not enough. Hana  apologised for the error.

Q37. Why did Dr Sadao tell the General everything about the man he had operated upon?
Ans. Dr Sadao could not report the arrival of the escaped prisoner at his doorstep. He wanted to get rid of the man for the sake of his wife. He explained his position to the General. He did not care for that man, but since he had operated upon the man he could not kill him. The
General praised his skill, called him indispensable and promised that he would allow nothing to happen to Dr Sadao.

Q38. Why, do you think, did the old General not want Dr Sadao to be arrested?
Ans. Dr Sadao had told the General that he could stand only one more such attack as he had that day. Then he would have to be operated upon. The General wanted Dr Sadao to operate upon him. He had no faith in the other surgeons trained by the Germans. So, he would not let Dr Sadao be arrested.

Q39. What plan did the old General suggest for getting rid of the ‘man’?
Ans. He thought that it would be best if the white man could be quietly killed—not by the doctor, but by someone who did not know him. He offered to send two of his private assassins any night to his home. These capable assassins would make no noise. They knew the trick of inward bleeding. They could even remove the body. Dr Sadao had to leave the outer partition of the room open and this made restless.

Q40. Why did Sadao sleep badly at night after meeting the General?
Ans. Sadao woke up time and again thinking he heard the rustling of footsteps, the sound of a twig broken or a stone displaced in the garden—or any noise such as men might make who carried a burden. This went on for three nights. Every night Sadao expected the assassins to come and this made him restless.

Q41. What plan did Dr Sadao devise to get rid of the man?
Ans. Dr Sadao devised the plan of letting the man escape to the nearest uninhabited island. He told the man everything. He put his boat on the shore with food and extra clothing. He advised the man to row to the little island not far from the coast. He could live there till he saw a Korean fishing boat pass by.

Q42. How was the plan of the prisoner’s escape executed?
Ans. Dr Sadao had put food and bottled water in his stout boat. He also put two quilts. After supper, he cheked the American again. He gave him his flashlight and told him to signal two flashes if he needed more food. One signal would mean he was OK He had to signal at sunset and not in the darkness. The man was dressed in Japanese clothes and his blond head was covered with a black cloth.

Q43. What did Sadao tell the General after a week? Why did he wait that long?
Ans. The General had undergone an emergency operation a week before. The gall bladder was involved. He was in critical state for twelve hours. Then he recovered slowly. After a week Sadao felt that the General was well enough to be spoken to about the prisoner. He told the General that the prisoner had escaped.

Q44. What did the General tell Dr Sadao about his promise to kill the prisoner for him?
Ans. Dr Sadao did not want to disturb the General much. So he simply said that the prisoner had escaped. The General at once remembered his promise. He confessed that he had been suffering a great deal. He thought of nothing but himself. He forgot his promise, but it was not lack of patriotism or dereliction of duty.

Q45. “I wonder why I could not kill him?” What makes Dr Sadao think so?
Ans. After the departure of the young American, Dr Sadao thinks of the other white faces he had “come across. The Americans were full of prejudice and he had found it bitter to live there. The white people were repulsive even in their kindness. It was relief to be openly at war with them. Then he remembered the youthful, haggard face of the prisoner. It was also white and repulsive. He thought it strange that he spared his enemy. He wondered why he could not kill him.

LONG ANSWER TYPE QUESTIONS
Q1. Why did Sadao Hoki go to America? What do you learn about his experiences there?
Ans. Sadao’s education was his father’s chief concern. So he had been sent at twenty-two to America to leam all that could be learnt of surgery and medicine. He studied there for eight years and returned to Japan at thirty. Before his father died, Sadao had become famous not only as a surgeon, but also as a scientist.
He had had great difficulty in finding a place to live in America because he was a Japanese. The Americans were full of prejudice and it had been bitter to live in it, knowing himself to be superior to them. An ignorant and dirty old woman at last consented to house him in her miserable home. He found her repulsive to him even in her kindness.
One of his American professors and his wife were kind people. They were anxious to do something for their few foreign students. But their rooms were quite small, the food was very bad, the professor was a dull person and his wife was a silly talkative woman.

Q2. How can you say that Dr Sadao’s father was a Japanese to the core?
Ans. Dr Sadao’s father had high dreams about the future of Japan. There was no limit to their future as it depended on what they made it. He never played or joked with his only son. But he spent infinite pains upon him. For the sake of the best possible medical education, he sent his son to America. Sadao met Hana there, but waited to fall in love with her until he was sure she was Japanese. His father would never have received her unless she had been pure in her race. Their marriage was arranged in the old Japanese way only after Sadao’s father had seen her when both of them had come home to Japan after finishing their education.
He was a Japanese every inch. The floor of his room was deeply matted. He would never sit on a chair or sleep in a foreign bed in his house. The quilt was covered with flowered silk and the lining was pure white silk. In short, everything here had been Japanese to please him.

Q3. What do you learn about Dr Sadao and Harm from the story ‘The Enemy’?
Ans. Sadao and Hana represent modem, enlightened and educated Japanese who get the benefit of American training in medical science, yet retain love and respect for their moth¬erland and its customs and traditions. He was an obedient and caring son who had deep regard for his father. He married Hana only after his father had seen her. Their marriage was arranged in the old Japanese way. They were perfectly happy and had two children. Even years after their marriage they retained the same love and affection for each other. Since Japan was at war with America, they considered the Americans as their enemies. The waves of the ocean had flung up a wounded young American to their doorstep. They wanted to put him back into the sea, but neither of them was able to do so. They brought the wounded man inside their house in spite of repulsion for him. Sadao had been trained not to let a man die if he could help him. The ethics of the medical profession forced him to save even his enemy. His wife Hana obeyed all his commands and instructions like a child though she suffered a lot internally.

Q4. What was the dilemma that Sadao faced when he saw a wounded, young white man washed to his doorstep? What solution did his wife, Hana, offer to resolve his (Sadao’s) predica¬ment?
Ans. The young white man was bleeding. He had a bullet wound on his lower back. He needed immediate medical attention. Dr Sadao, an eminent surgeon, could do so. But if they sheltered a white man in their house, they would be arrested. On the other hand, if they tinned him over as a prisoner, he would certainly die. Neither of them could put him back into the sea and get rid of him. They were true humanist. So, they hesitated.
Sadao declared that being an American, the man was his enemy. He would have handed him over to the police if he had been hale and hearty. But since he was wounded… He left the sentence unfinished implying that he could not do so as he had been trained not to let a man die if he could help him.
Hana suggested that they must carry the man inside the house. They must tell the ser¬vants that they intended to hand him over to the police. She reminded her husband of his position and the children. It would endanger all of them if they did not hand that man over as a prisoner of war. His doubts were removed and they decided to carry the man into their house.

Q5. How did Dr Sadao take the man inside his house and try to save him?
Ans. Dr Sadao and Hana lifted the man together. He was very light. His arms were hanging
down. They carried him up the steps and into the side door of the house. This door opened •
into a passage. Down the passage, they carried him towards an empty bedroom. They laid the man on the deeply matted floor. The man was quite dirty, so Dr Sadao suggested that he should be washed.
The utter pallor of the man’s unconscious face moved Dr Sadao first to stoop and feel his pulse. It was faint, but it was there. Then he put his hand against the man’s cold breast.
The heart too was yet alive. He observed that the man would die unless he was operated upon immediately. He left the room to bring his instruments to perform an emergency operation to save the man’s life.

Q6. How did the servants initially react to the presence of a white man in their masters house?
Ans.When Dr Sadao told the cook and the gardener about the wounded young white man, they
had brought inside the house, the two servants were frightened and puzzled. The *
superstitious old gardener looked so annoyed that he pulled the few hairs on his upper lip.
He bluntly told Hana that the master ought not to heal the wound of that white man. He said that the white man ought to die. First he was shot. Then the sea caught him and wounded him with her rocks. If the master healed what the gun and the sea had done, they would take revenge on them.
Even the maid, Yumi, refused to wash the man though Hana cried at her severely and told her to do what the master had commanded her to do. The servants seemed to be in a defiant mood. The fierce look of resistance upon Yumi’s dull face frightened Hana. She thought that the servants might report something that was not as it happened. She main¬tained her dignity and told the maid that they wanted to bring him to his senses so that they could turn him over as a prisoner. Even this explanation failed to convince Yumi and she refused to do anything for the white man.

Q7. What was the change in the mood of open defiance of their master on the part of domestic staff as time passed and the white man was kept in Dr Sadao’s house ?
Ans. Dr Sadao not only kept the young white man at his home, but also operated upon him. It was the third day after the operation. The servants continued their open defiance of their master and did not enter the white man’s room. Hana served him herself. Hana told Sadao what the servants had conveyed through Yumi. The domestic staff felt that they could not stay there if their. master sheltered that man any more. They accused them of having forgotten to think of their own countiy because they had lived for a long time in America. They thought that their master and mistress liked Americans. Dr Sadao tried to clarify his position as a man and as a doctor. Hana told him that the servants could not understand this subtle distinction.
”Somehow the household dragged on. The servants grew more watchful day by day. They were careful in their courtesy as ever but their eyes were cold. The old gardener was the most vocal. He taunted that their master knew very well what he ought to do. He was sore why Sadao had not let the young man bleed when he was so near to death. The cook remarked contemptuously that the young master was so proud of his skill to save life that he saved any life. Yumi added that they must think of the children. She enquired: “What will be their fate if their father is condemned as a traitor?”
Since the white man was not handed over to the police, even after a week, all the servants left on the seventh day after that.

Q8. Hana was a loving, caring, devoted and obedient wife who was quite anxious about her husband’s wellbeing, position and reputation? Discuss.
Ans. Hana is the alter ego of her husband, Dr Sadao Hoki. She has adapted herself to his ways. She knows that saving a life is a mission for him and when he is attending on his patient, he forgets everything else—even Hana herself. Even years after their marriage, they retain the same love and affection for each other.
She cared for him a lot and would not let him stand outside in the cold foggy February night. She was a bit sentimental, yet pragmatic in her approach. She was quick to judge what went on in her husband’s mind and suggested solutions. She maintained her dignity when the servants showed resistance and open defiance. As an obedient and devoted wife, she carried out all the orders and instructions of her husband. She washed the wounded white man, gave him anaesthesia and later on food.
She was worried about her husband’s safety, position and reputation. Initially, she suggested to throw the man back into the sea. She was afraid that the servants might misreport. Her fears are exhibited clearly when a messenger in uniform arrives from the palace. In order to calm down her fears, Dr Sadao decides to get rid of the white man anyhow. In short, she is an ideal life partner.

Q9. What impression do you form of Dr Sadao as a man and as a surgeon from your reading of the story ‘The Enemy’?
Ans. Dr Sadao Hoki was a true Japanese like his father. He was a brave boy who obeyed and respected his father and loved Japanese culture, tradition and people. He was intelligent and hard working and studied surgery and medicine in America for eight years. He mar¬ried a Japanese girl, Hana, whom he had met in America. But he waited for his father’s approval and their marriage was arranged in the old Japanese way after they had re¬turned home to Japan. They had two children. He still loved his wife as warmly as ever. He returned home at fixed hours.
Dr Sadao was an eminent surgeon as well as scientist. The old General had full faith in him. He was not sent abroad with the troops because the old General might need an operation. Dr Sadao was called even at odd hours from the palace. Dr Sadao was a real doctor. He would not let a man die if he could help him. That is why he cured even an “enemy” of bullet wound and did not hand him over to the police. He faced a great risk to his position and life by sheltering the man. Since Dr Sadao could not kill the man himself, he sought the help of the old General to get rid of him. When that plan failed, he let the prisoner escape in order to calm down the fears of his wife and let the household run properly. It may be a blemish from a narrow patriotic angle but a sensitive soul can’t take back what he has given.

Q10. Under what circumstances did Dr Sadao let the wounded white man escape? Was it lack of national loyalty, professional ego and sentimentality, human consideration or just an attempt to save his skin?
Ans. Hr Sadao had no love for the repulsive Americans and he considered them his enemies. Unfortunately, the sea-waves pushed a wounded white man to his doorstep. He knew that the best possible thing was to throw him back into the sea. He could not handover a wounded ‘enemy’ to police because he would certainly die. Being a doctor, he could save him and not kill him. His efforts to get him removed with the help of the old General’s private assassins did not bear fruit.
He was under a severe strain. His domestic servants had left him. His wife had to do unaccustomed labour and run the household. Moreover, his wife was anxious about his safety. They might be arrested for harbouring an enemy prisoner of war and condemned as traitors.
Dr Sadao let the man escape in the larger interest of professional ethics and human consideration. He rose above narrow national loyalty and sentimentality. He did not think of himself as the General had already assured him that no harm would be caused to him. The matter remained unreported and closed from public eyes and ears. The servants returned after the white man had “left”. Everything became normal again.

Q11. Comment on the role of the old General in the story ‘The Enemy’.
Ans. The old General plays an important role in the story. He is being treated medically for a condition which might need an operation any time. Since he has full faith in Dr Sadao, he is kept back in Japan. Dr Sadao is indispensable to the General. He assures Sadao that nothing will happen to him and he will not be arrested.
The arrival of the messenger rouses Hana’s worst fears. She thinks that police has come to arrest her husband. Dr Sadao gets distressed at her anxiety and decides to get rid of the white man for her sake. When Dr Sadao confides in the General, the latter promises to send two of his private assassins to remove the man from the scene.
The old General has an unsual sense of humour as well as frankness and ability to admit his mistake. Dr Sadao keeps on waiting for three nights for the assassins who fail to turn up. He loses sleep and rest. Finally he lets the white man escape.
When Dr Sadao tells the General that the man has escaped, the General admits that he forgot his promise. He was suffering a great deal and thought of nothing but himself. It was careless of him but not lack of patriotism or dereliction of duty, It is his self-absorption and instinct of preserving himself that saves Dr Sadao and his family from being arrested.

Q12. The ending of the story ‘The Enemy’ epitomises the attitude of a Japanese towards Americans during the war. Elucidate.
OR
Comment on the ending of the story ‘The Enemy’.
Ans. The ending of the story, ‘The Enemy’ is highly artistic. The old General, recovering from the operation, promises that Dr Sadao will be rewarded as he is a good man. Dr Sadao has his reward when he finds that his prisoner has gone away safely from the island. He now recalls all the other white faces he ever came across. The professor, at whose house he met Hana, was a dull man and his wife had been a silly, talkative woman, in spite of her wish to be kind. His old teacher of anatomy had been insistent on ‘mercy with the knife’. He remembered the face of his fat and slatterly landlady whom he had despised for being ignorant and dirty. He remembered the difficulties he faced in finding a place to live in America because he was a Japanese. The Americans were full of prejudice and, it had been bitter to live in America. He found the white people repulsive. It was a relief to be openly at war with them. Then he remembered the youthful, haggard face of the prisoner. It was also white and repulsive. He thought it strange that he spared his enemy. He is left wondering why he could not kill the white man “his enemy”.

Q13. Do you think the title ‘The Enemy’ is appropriate? Give reasons in support of your answer.
Ans. The title ‘The Enemy’ is quite appropriate and highly suggestive. It focuses our attention on the wounded man who is incidentally washed ashore to the doorstep of a famous Japanese surgeon, Dr Sadao Hoki during the war.
The first reaction of the Japanese pair is typical of average, patriotic Japanese who hate their white enemies. However, the doctor in Sadao prompts him to bring the man inside his house and cure him. The doctor’s involvement with the white enemy annoys the domestic staff who show open defiance and resistance. The doctor faces grave danger to his position, safety, name, fame and family by harbouring the enemy. He could be condemned as a traitor and killed.
In spite of all the odds, the doctor finds himself emotionally unable to hand him over to the police. He has no love for the man. He regards him his enemy, yet he can’t kill him. He tells the old General how he operated on the white man and saved him. The General is all praise for his skill, hopes for his own successful operation at his hand, and promises to kill the man for him.
The doctor faces a lot of tension—mental, emotional and physical. He passes sleepless nights waiting for the assassins, who never turn up. Meanwhile, ‘the enemy’ recovers and the doctor devises means to let him escape in order to get rid of him. At the end of the story he is left wondering why he could not kill that man.

Q14. What was the General’s plan to get rid of the American prisoner ? Was it executed ? What traits of the General’s character are highlighted in the lesson ‘The Enemy’?[All India 2014]
Ans. The General made a plan to get rid of the American prisoner by sending his personal assassins to kill the prisoner. He also wanted to remove the body of American prisoner from Sadao’s house. But, unfortunately he could not succeed in his attempt. The plan was i not executed. The General could not send the assassins.
The General had an unusual sense of humour as well as frankness and ability to admit his mistake. Dr. Sadao keeps on waiting for three nights for the assassins who fail to turn up. He loses his rest and sleep. Finally he lets the white man escape. When Dr. Sadao tells the General that the man has escaped, the General admits that he forgot his promise. It was carelessness of him but not the lack of patriotism. It is his self-absorption and instinct of preserving himself that saves Dr. Sadao and his family being arrested.
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NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions

NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions

Topics and Subtopics in NCERT Solutions for Class 12 Chemistry Chapter 2 Solutions:

 Section Name Topic Name
2 Solutions
2.1 Types of Solutions
2.2 Expressing Concentration of Solutions
2.3 Solubility
2.4 Vapour Pressure of Liquid Solutions
2.5 Ideal and Non-ideal Solutions
2.6 Colligative Properties and Determination of Molar Mass
2.7 Abnormal Molar Masses

NCERT TEXTBOOK QUESTIONS SOLVED

2.1. Calculate the mass percentage of benzene (C6H6) and carbon tetrachloride (CCl4) if 22 g of benzene is dissolved in 122 g of carbon tetrachloride.
Ans: Mass of solution = Mass of C6H6 + Mass of CCl4
= 22 g+122 g= 144 g
Mass % of benzene = 22/144 x 100 =15.28 %
Mass % of CCl4 = 122/144 x 100 = 84.72 %

2.2. Calculate the mole fraction of benzene in solution containing 30% by mass in carbon tetrachloride.
Ans: 30% by mass of C6H6 in CCl4 => 30 g C6H6 in 100 g solution
.’. no. of moles of C6H6,(nC6h6) = 30/78 = 0.385
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Textbook Questions Q2

2.3. Calculate the molarity of each of the following solutions
(a) 30 g of Co(NO3)26H2O in 4·3 L of solution
(b) 30 mL of 0-5 M H2SO4 diluted to 500 mL.
Ans:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Textbook Questions Q3

2.4. Calculate the mass of urea (NH2CONH2) required in making 2.5 kg of 0.25 molal aqueous solution.
Ans: 0.25 Molal aqueous solution to urea means that
moles of urea = 0.25 mole
mass of solvent (NH2CONH2) = 60 g mol-1
.’. 0.25 mole of urea = 0.25 x 60=15g
Mass of solution = 1000+15 = 1015g = 1.015 kg
1.015 kg of urea solution contains 15g of urea
.’. 2.5 kg of solution contains urea =15/1.015 x 2.5 = 37 g

2.5. Calculate
(a) molality
(b) molarity and
(c) mole fraction of KI if the density of 20% (mass/mass) aqueous KI solution is 1·202 g mL-1.
Ans:
Step I. Calculation of molality of solution
Weight of KI in 100 g of the solution = 20 g
Weight of water in the solution = 100 – 20 = 80 g = 0-08 kg
Molar mass of KI = 39 + 127 = 166 g mol-1.
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Textbook Questions Q5
Step II. Calculation of molarity of solution
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Textbook Questions Q5.1
Step III. Calculation of mole fraction of Kl
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Textbook Questions Q5.2

2.6. HS, a toxic gas with rotten egg like smell, is used for the qualitative analysis. If the solubility of H2S in water at STP is 0.195 m, calculate Henry’s law constant.
Ans: Solubility of H2S gas = 0.195 m
= 0.195 mole in 1 kg of solvent
1 kg of solvent = 1000g
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Textbook Questions Q6

2.7. Henry’s law constant for CO2 in water is 1.67 x 108 Pa at 298 K. Calculate the quantity of CO2 in 500 mL of soda water when packed under 2.5 atm CO2 pressure at 298 K.
Ans.:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Textbook Questions Q7

2.8 The vapour pressures of pure liquids A and B are 450 mm and 700 mm of Hg respectively at 350 K. Calculate the composition of the liquid mixture if total vapour pressure is 600 mm of Hg. Also find the composition in the vapour phase.
Ans:
Vapour pressure of pure liquid A (\({ P }_{ A }^{ \circ }\)) = 450 mm
Vapour pressure of pure liquid B (\({ P }_{ B }^{ \circ }\)) = 700 mm
Total vapour pressure of the solution (P) = 600 mm
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Textbook Questions Q8

2.9. Vapour pressure of pure water at 298 K is 23.8 m m Hg. 50 g of urea (NH2CONH2) is dissolved in 850 g of water. Calculate the vapour pressure of water for this solution and its relative lowering.
Ans:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Textbook Questions Q9

2.10. Boiling point of water at 750 mm Hg is 99.63°C. How much sucrose is to be added to 500 g of water such that it boils at 100°C.
Ans:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Textbook Questions Q10

2.11 Calculate the mass of ascorbic acid (vitamin C, C6H8O6) to be dissolved in 75 g of acetic acid to lower its melting point by 1·5°C. (Kf for CH3COOH) = 3·9 K kg mol-1)
Ans:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Textbook Questions Q11

2.12. Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL of water at 37°C.
Ans:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Textbook Questions Q12

NCERT EXERCISES

2.1. Define the terra solution. How many types of solutions are formed? Write briefly about each type with an example.
Sol: A solution is a homogeneous mixture of two or more chemically non-reacting substances. Types of solutions: There are nine types of solutions.
Types of Solution Examples
Gaseous solutions
(a) Gas in gas Air, mixture of 02 and N2, etc.
(b) Liquid in gas Water vapour
(c) Solid in gas Camphor vapours in N2 gas, smoke etc.
Liquid solutions
(a) Gas in liquid C02 dissolved in water (aerated water), and 02 dissolved in water, etc.
(b) Liquid in liquid Ethanol dissolved in water, etc.
(c) Solid in liquid Sugar dissolved in water, saline water, etc.
Solid solutions
(a) Gas in solid Solution of hydrogen in palladium
(b) Liquid in solid Amalgams, e.g., Na-Hg
(c) Solid in solid Gold ornaments (Cu/Ag with Au)

2.2. Suppose a solid solution is formed between two substances, one whose particles are very large and the other whose particles are very small. What type of solid solution is this likely to be ?
Sol: The solution likely to be formed is interstitial solid solution.

2.3 Define the following terms:
(i) Mole fraction
(ii) Molality
(iii) Molarity
(iv) Mass percentage
Sol: (i) Mole fraction: It is defined as the ratio of the number of moles of the solute to the total number of moles in the solution. If A is the number of moles of solute dissolved in B moles of solvent, then Mole fraction of solute
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q3
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q3.1
(ii) Molality: It is defined as die number of moles of a solute present in 1000g (1kg) of a solvent.
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q3.2
NOTE: Molality is considered better way of expressing concentration of solutions, as compared to molarity because molality does not change with change in temperature since the mass of solvent does not vary with temperature,
(iii) Molarity: It is defined as the number of moles of solute present in one litre of solution.
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q3.3
NOTE: Molarity is the most common way of expressing concentration of a solution in laboratory. However, it has one disadvantage. It changes with temperature because volume of a solution alters due to expansion and contraction of the liquid with temperature.
(iv) Mass percentage: It is the amount of solute in grams present in 100g of solution.
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q3.4

Free online chemical calculator. Molarity Calculate Chemistry, mass or volume.

2.4. Concentrated nitric acid used in the laboratory work is 68% nitric acid by mass in aqueous solution. What should be the molarity of such a sample of acid if the density of the solution is 1·504 g mL-1 ?
Sol: Mass of HNO3 in solution = 68 g
Molar mass of HNO3 = 63 g mol-1
Mass of solution = 100 g
Density of solution = 1·504 g mL-1
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q4

2.5. A solution of glucose in water is labelled as 10% w/w, what would be the molality and mole fraction of each component in the solution? If the density of solution is 1 .2 g m L-1, then what shall be the molarity of the solution?
Sol: 10 percent w/w solution of glucose in water means 10g glucose and 90g of water.
Molar mass of glucose = 180g mol-1 and molar mass of water = 18g mol-1
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q5

NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q5.1

2.6. How many mL of 0.1 M HCl are required to react completely with 1 g mixture of Na2C0and NaHCOcontaining equimolar amounts of both?
Sol: Calculation of no. of moles of components in the mixture.
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q6

NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q6.1

2.7. Calculate the percentage composition in terms of mass of a solution obtained by mixing 300 g of a 25% and 400 g of a 40% solution by mass.
Sol:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q7

2.8. An antifreeze solution is prepared from 222.6 g of ethylene glycol, (C2 H6O2 ) and200 g of water. Calculate the molality of the solution. If the density of the solution is 1.072 g mL-1, then what shall be the molarity of the solution?
Sol:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q8

NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q8.1

2.9. A sample of drinking water was found to be severely contaminated with chloroform (CHCl3), supposed to be a carcinogen. The level of contamination was 15 ppm (by mass).
(i) express this in percent by mass.
(ii) determine the molality of chloroform in the water sample.
Sol: 15 ppm means 15 parts in million (106) by mass in the solution.
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q9

2.10. What role does the molecular interaction play in solution of alcohol in water?
Sol: In case of alcohol as well as water, the molecules are interlinked by intermolecular hydrogen bonding. However, the hydrogen bonding is also present in the molecules of alcohol and water in the solution but it is comparatively less than both alcohol and water. As a result, the magnitude of attractive forces tends to decrease and the solution shows positive deviation from Raoult’s Law. This will lead to increase in vapour pressure of the solution and also decrease in its boiling point.

2.11. Why do gases always tend to be less soluble in liquids as the temperature is raised?
Sol: When gases are dissolved in water, it is accompanied by a release of heat energy, i.e., process is exothermic. When the temperature is increased, according to Lechatlier’s Principle, the equilibrium shifts in backward direction, and thus gases becomes less soluble in liquids.

2.12. State Henry’s law and mention some of its important applications.
Sol:
Henry’s law: The solubility of a gas in a liquid at a particular temperature is directly proportional to the pressure of the gas in equilibrium with the liquid at that temperature.
or
The partial pressure of a gas in vapour phase is proportional to the mole fraction of the gas (x) in the solution. p = KHX
where KH is Henry’s law constant.
Applications of Henry’s law :
(i) In order to increase the solubility of CO2 gas in soft drinks and soda water, the bottles are normally sealed under high pressure. Increase in pressure increases the solubility of a gas in a solvent according to Henry’s Law. If the bottle is opened by removing the stopper or seal, the pressure on the surface of the gas will suddenly decrease. This will cause a decrease in the solubility of the gas in the liquid i.e. water. As a result, it will rush out of the bottle producing a hissing noise or with a fiz.
(ii) As pointed above, oxygen to be used by deep sea divers is generally diluted with helium inorder to reduce or minimise the painfril effects during decompression.
(iii) As the partial pressure of oxygen in air is high, in lungs it combines with haemoglobin to form oxyhaemoglobin. In tissues, the partial pressure of oxygen is comparatively low. Therefore, oxyhaemoglobin releases oxygen in order to carry out cellular activities.

2.13. The partial pressure of ethane over a solution containing 6.56 × 10-3 g of ethane is 1 bar. If the solution contains 5.00 × 10-2 g of ethane, then what shall be the partial pressure of the gas?
Sol:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q13

2.14. According to Raoult’s law, what is meant by positive and negative deviaitions and how is the sign of ∆solH related to positive and negative deviations from Raoult’s law?
Sol: Solutions having vapour pressures more than that expected from Raoult’s law are said to exhibit positive deviation. In these solutions solvent – solute interactions are weaker and ∆solH is positive because stronger A – A or B – B interactions are replaced by weaker A – B interactions. Breaking of the stronger interactions requires more energy & less energy is released on formation of weaker interactions. So overall ∆sol H is positive. Similarly ∆solV is positive i.e. the volume of solution is some what more than sum of volumes of solvent and solute.
So there is expansion in volume on solution formation.
Similarly in case of solutions exhibiting negative deviations, A – B interactions are stronger than A-A&B-B. So weaker interactions are replaced by stronger interactions so , there is release of energy i.e. ∆sol H is negative.

2.15. An aqueous solution of 2 percent non-volatile solute exerts a pressure of 1·004 bar at the boiling point of the solvent. What is the molecular mass of the solute ?
Sol:
According to Raoult’s Law,
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q15

2.16  Heptane and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid components are 105.2 kPa and 46.8 kPa respectively. What will be the vapour pressure of a mixture of 26.0 g of heptane and 35.0 g of octane?
Sol.
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q16

NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q16.1

2.17.  The vapour pressure of water is 12.3 kPa at 300 K. Calculate vapour pressure of 1 molal solution of a non-volatile solute in it
Sol: 1 molal solution of solute means 1 mole of solute in 1000g of the solvent.
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q17

2.18. Calculate the mass of a non-volatile solute (molecular mass 40 g mol-1) that should be dissolved in 114 g of octane to reduce its pressure to 80%. (C.B.S.E. Outside Delhi 2008)
Sol: According to Raoult’s Law,
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q18

2.19. A solution containing 30g of non-volatile solute exactly in 90 g of water has a vapour pressure of 2.8 kPa at 298 K. Further, 18g of water is then added to the solution and the new of vapour pressure becomes 2.9 kPa at 298 K. Calculate
(i) molar mass of the solute.
(ii) vapour pressure of water at 298 K.
Sol: Let the molar mass of solute = Mg mol-1
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q19

NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q19.1

NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q19.2

2.20. A 5% solution (by mass) of cane sugar in water has freezing point of 271 K. Calculate the freezing point of 5% glucose in water if freezing point of pure water is 273.15 K.
Sol: Mass of sugar in 5% (by mass) solution means 5gin 100g of solvent (water)
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q20

2.21. Two elements A and B form compounds having formula AB2 and AB4. When dissolved in 20g of benzene (C6H6), 1 g of AB2 lowers the freezing point by 2.3 K whereas 1.0 g of AB4 lowers it by 1.3 K. The molar depression constant for benzene is 5.1 K kg mol-1. Calculate atomic masses of A and B.
Sol:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q21

2.22. At 300 K, 36 g glucose present per litre in its solution has osmotic pressure of 4·98 bar. If the osmotic pressure of the solution is 1·52 bar at the same temperature, what would be its concentration?
Sol:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q22

NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q22.1

2.23. Suggest the most important type of intermolecular attractive interaction in the following pairs:
(i) n-hexane and n-octane
(ii) I2 and CCl4.
(iii) NaCl04 and water
(iv) methanol and acetone
(v) acetonitrile (CH3CN) and acetone (C3H60)
Sol: (i) Both w-hexane and n-octane are non-polar. Thus, the intermolecular interactions will be London dispersion forces.
(ii) Both I2 and CCl4 are non-polar. Thus, the intermolecular interactions will be London dispersion forces.
(iii) NaCl04 is an ionic compound and gives Na+ and Cl04 ions in the Solution. Water is a polar molecule. Thus, the intermolecular interactions will be ion-dipole interactions.
(iv) Both methanol and acetone are polar molecules. Thus, intermolecular interactions will be dipole-dipole interactions.
(v) Both CH3CN and C3H6O are polar molecules. Thus, intermolecular interactions will be dipole-dipole interactions.

2.24. Based on solute solvent interactions, arrange the following in order of increasing solubility in n-octane and explain. Cyclohexane, KCl, CH3OH, CH3CN.
Sol: n-octane (C8H18) is a non-polar liquid and solubility is governed by the principle that like dissolve like. Keeping this in view, the increasing order of solubility of different solutes is:
KCl < CH3OH < CH3C=N < C6H12 (cyclohexane).

2.25. Amongst the following compounds, identify which are insoluble, partially soluble and highly soluble in water?
(i) phenol
(ii) toluene
(iii) formic acid
(iv) ethylene glycol
(v) chloroform
(vi) pentanol
Sol: (i) Phenol (having polar – OH group) – Partially soluble.
(ii) Toluene (non-polar) – Insoluble.
(iii) Formic acid (form hydrogen bonds with water molecules) – Highly soluble.
(iv) Ethylene glycol (form hydrogen bonds with water molecules) Highly soluble.
(v) Chloroform (non-polar)- Insoluble.
(vi) Pentanol (having polar -OH) – Partially soluble.

2.26. If the density of lake water is 1·25 g mL-1, and it contains 92 g of Na+ ions per kg of water, calculate the molality of Na+ ions in the lake. (C.B.S.E. Outside Delhi 2008)
Sol:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q26

2.27. If the solubility product of CuS is 6 x 10-16, calculate the maximum molarity of CuS in aqueous solution.
Sol:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q27

2.28. Calculate the mass percentage of aspirin (C9H8O4 in acetonitrile (CH3CN) when 6.5g of CHO is dissolved in 450 g of CH3CN.
Solution:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions-28

2.29. Nalorphene (C19H21NO3), similar to morphine, is used to combat withdrawal symptoms in narcotic users. Dose of nalorphene generally given is 1.5 mg. Calculate the mass of 1.5 x 10-3 m aqueous solution required for the above dose.
Solution:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q29

2.30. Calculate the amount of benzoic acid (C5H5COOH) required for preparing 250 mL of 0· 15 M solution in methanol.
Solution:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q30

2.31. The depression in freezing point of water observed for the same amount of acetic acid, trichloroacetic acid and trifluoroacetic acid increases in the order given above. Explain briefly.
Solution:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions-31
Fluorine being more electronegative than chlorine has the highest electron withdrawing inductive effect. Thus, triflouroacetic acid is the strongest trichloroacetic acid is second most and acetic acid is the weakest acid due to absence of any electron withdrawing group. Thus, F3CCOOH ionizes to the largest extent while CH3COOH ionizes to minimum extent in water. Greater the extent of ionization greater is the depression in freezing point. Hence, the order of depression in freezing point will be CH3COOH < Cl3CCOOH < F3CCOOH.

2.32. Calculate the depression in the freezing point of water when 10g of CH3CH2CHClCOOH is added to 250g of water. Ka = 1.4 x 1o-3 Kg = 1.86 K kg mol-1.

Solution:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions-32
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions-32.1

Calculate the Dilution Factor by dividing the total diluted sample volume by the original sample volume using this dilution factor formula.

2.33. 19.5g of CH2FCOOH is dissolved in 500g of water. The depression in the freezing point of water observed is 1.0°C. Calculate the van’s Hoff factor and dissociation constant of fluoroacetic acid.

Solution:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions-33

2.34. Vapour pressure of water at 293 K is 17·535 mm Hg. Calculate the vapour pressure of water at 293 K when 25 g of glucose is dissolved in 450 g of water.
Solution:
According to Raoult’s Law,
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q34

2.35. Henry’s law constant for the molality of methane in benzene at 298 K is 4.27 x 105 mm Hg. Calculate the solubility of methane in benzene at 298 K under 760 mm Hg.

Solution:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions-35

2.36. 100g of liquid A (molar mass 140 g mol-1) was dissolved in 1000g of liquid B (molar mass 180g mol-1). The vapour pressure of pure liquid B was found to be 500 torr. Calculate the vapour pressure of pure liquid A and its vapour pressure in the solution if the total vapour pressure of the solution is 475 torr.

Solution:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions-36

2.37. Vapour pressures of pure acetone and chloroform at 328 K are 741.8 mm Hg and 632.8 mm Hg respectively. Assuming that they form ideal solution over the entire range of composition, plot Ptotal, Pchlroform and Pacetone as a function of χacetone. The experimental data observed for different compositions of mixtures is:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions-37q
Plot this data also on the same graph paper. Indicate whether it has positive deviation or negative deviation from the ideal solution.

Solution:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions-37

2.38. Benzene and toluene form ideal solution over the entire range of composition. The vapour pressure of pure benzene and toluene at 300 K are 50.71 mm Hg and 32.06 mm Hg respectively. Calculate the mole fraction of benzene in vapour phase if 80g of benzene is mixed with 100g of toluene.

Solution:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions-38

2.39. The air is a mixture of a number of gases. The major components are oxygen and nitrogen with an approximate proportion of 20% is to 79% by volume at 298 K. The water is in equilibrium with air at a pressure of 10 atm. At 298 K if Henry’s law constants for oxygen and nitrogen are 3.30 x 107 mm and 6.51 x 107 mm respectively, calculate the composition of these gases in water.

Solution:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q39
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions-39.1

2.40. Determine the amount of CaCl2 (i = 2.47) dissolved in 2.5 litre of water such that its osmotic pressure is 0.75 atm at 27°C.

Solution:
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions-40
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions-40.1

2.41. Determine the osmotic pressure of a solution prepared by dissolving 25 mg of K2SO4 in 2 litre of water at 25°C, assuming that it is completely dissociated. (C.B.S.E. 2013)
Solution:
Step I. Calculation of Van’t Hoff factor (i)
K2SO4 dissociates in water as :
NCERT Solutions For Class 12 Chemistry Chapter 2 Solutions Exercises Q41

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NCERT Solutions For Class 11 Biology Biomolecules

NCERT Solutions For Class 11 Biology Biomolecules

Topics and Subtopics in NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules:

Section Name Topic Name
9 Biomolecules
9.1 How to Analyse Chemical Composition?
9.2 Primary and Secondary Metabolites
9.3 Biomacromolecules
9.4 Proteins
9.5 Polysaccharides
9.6 Nucleic Acids
9.7 Structure of Proteins
9.8 Nature of Bond Linking Monomers in a Polymer
9.9 Dynamic State of Body Constituents – Concept of Metabolism
9.10 Metabolic Basis for Living
9.11 The Living State
9.12 Enzymes
9.13 Summary

NCERT Solutions Class 11 BiologyBiology Sample Papers

NCRT TEXTBOOK QUESTIONS SOLVED

1. What are macromolecules? Give examples.
Solution: Macromolecules are large high molecular weight substances with complex molecular structure and occur in colloidal state (being insoluble) in intracellular fluid. These are formed by polymerization of large number of micromolecules. Polysaccharides, proteins and nucleic acids are few examples.

2. Illustrate a glycosidic, peptide, and a phospho- diester bond.
Solution. (i) Glycosidic bond is the type of chemical linkage between the monosaccharide units of disaccharides, oligosaccharides and polysaccharides, which is formed by the removal of a molecule of water.
NCERT Solutions For Class 11 Biology Biomolecules Q2
(ii)Peptide bonds are formed by the reaction between carboxyl (- COOH) of one amino acid and amino (- NH2) group of other amino acid with the elimination of water.
NCERT Solutions For Class 11 Biology Biomolecules Q2.1
(iii) In a polynucleotide chain, adjacent nucleotides are joined together by a bond called phosphodiester bond. This bond links a phosphate group and sugar group of two adjacent nucleotides by means of an oxygen bridge.
NCERT Solutions For Class 11 Biology Biomolecules Q2.2

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3. What is meant by tertiary structure of proteins?
Solution: The helical polypeptide molecule may fold on itself and assume a complex but specific form-spherical, rod-like or any form in between these. These geometrical shapes,are known as tertiary (3°) structure of protein molecules. The coils and folds of the polypeptide molecules are so arranged as to hide the non-polar amino acid chains inside and to expose the polar side chains. The tertiary structure of a protein brings distant amino acid side chains nearer to form active sites of enzymatic proteins. The tertiary structure is maintained by weak bonds such as hydrogen, ionic, disulphide and hydrophilic – hydrophobic bonds, formed between one part of a polypeptide and another. This structure is easily disrupted by pH, temperature and chemicals stopping the function of proteins.

The protein molecular weight calculator is a simple tool for computing the molecular mass of a protein using a list of its amino acids.

4. Find and write down structures ©f 10 interesting small molecular weight biomolecules.
Solution: Interesfing small molecular weight biomolecules are minerals (like sodium, potassium, calcium, zinc, iodine etc), gases (like Oz, N2, C02, NH3) sugars – (ribose, deoxyribose, glucose, fructose), lipids, amino acids, nucleotides (pyrimidines & purine). Structures of 10 interesting small molecular weight biomolecules are as follows:
NCERT Solutions For Class 11 Biology Biomolecules Q4

NCERT Solutions For Class 11 Biology Biomolecules Q4.1

NCERT Solutions For Class 11 Biology Biomolecules Q4.2

NCERT Solutions For Class 11 Biology Biomolecules Q4.3

5. Proteins have primary structure. If you are given a method to know which amino acid is at either of two termini (ends) of a protein, can you connect this information to purity or homogeneity of a protein?
Solution: There are several methods provided by several scientists to find out the sequence of amino acids. Frederick Sanger proposed Sanger’s reagent to know the amino acid sequence in a polypeptide chain.
Sanger used 1-fluoro 2, 4 dinitrobenzene (FD NB) to determine insulin structure. FDNB specifically binds with N-terminal amino acid to form a dinitrophenyl (DNP) derivative of peptide. This DNP- derivative peptide can be identified by chromatography. The identified sequence of amino acids shows the homogeneity of a protein molecule.

6. Find out and make a list of proteins used as therapeutic agents. Find other applications of proteins.
Solution: Proteins used as therapeutic agents are: thrombin, fibrinogen, enkephalins, antigens, antibodies, streptokinase, protein tyrosine kinase, diastase, renin, insulin, oxytocin, vasopressin etc. Proteins are also used in cosmetics, dairy industries, textile industries, research techniques, biological buffers etc.

7. Explain the composition of triglycerides. jSfflTriacylglycerols (triglycerides) are the esters of glycerol with fatty acids.
Solution: They are insoluble in water and non-polar in character and commonly known as neutral fats. The neutral or depot fats are composed of carbon, hydrogen and oxygen like carbohydrates but have far fewer oxygen atoms than carbon atoms unlike the carbohydrates.
NCERT Solutions For Class 11 Biology Biomolecules Q7
(i) Glycerol – A glycerol molecule has 3
carbons, each bearing a hydroxyl (-OH) group. .
(ii) Fatty acids – A fatty acid molecule is an unbranched chain of carbon atoms with each carbon atom (C) forming four bonds to other atoms. It has a carboxyl group- COOH at one end and hydrogen atom (H) bonded to all or most carbon atoms forming a hydrogen chain. The carbon- hydrogen bonds are non-polar. Therefore, the hydrocarbon chain does not dissolve in water. Because the carboxyl group contains the polar C = O and OFI groups. It tends to dissolve in water even though the rest of fatty acid molecule will not. Triacylglycerols of plants, in general, have higher content of unsaturated fatty acids as compared to that of animals.

8. Can you describe what happens when milk is converted into curd or yoghurt, from your understanding of proteins.
Solution: Milk is converted into curd or yoghurt due to denaturation of proteins. In denaturation, disruption of bonds that maintains secondary and tertiary structure leads to the conversion of globular proteins into fibrous proteins. This involves a change in physical, chemical and biological properties of protein molecules.

9. Can you attempt building models of biomolecules using commercially available atomic models (Ball and stick models).
Solution: Yes, models of biomolecules can be prepared using commercially available atomic models.
Ball and stick models and space filling models are 3D or spatial molecular models which serve to display the structure of chemical products and substances or biomolecules. With ball and stick models, the centers of the atoms are connected by straight lines which represent the covalent bonds. Double and triple bonds are often represented by springs which form curved connections between the balls. The bond angles and bond lengths reflect the actual relationships, while the space occupied by the atoms is either not represented at all or only denoted essentially by the relative sizes of the spheres.

10. Attempt titrating an amino acid against a weak base and discover the number of dissociating (ionizable) functional groups in the amino acid.
Solution: The existence of different ionic forms of amino acids can be easily understood by the titration curves. The number of dissociating functional group is one in case of neutral and basic amino acids and two in case of acidic amino acids.

11. Draw the structure of the amino acid, alanine.
Solution:
NCERT Solutions For Class 11 Biology Biomolecules Q11

12. What are gums made of ? Is fevicol different ?
Solution: Gums are hetero-polysaccharides (poly-mers) of large number of different monosac-charide units. Yes, fevicol is a different kind of polymer. It is a synthetic sticky substance called resin which is manufactured by esteri-fication of organic compounds.

13. Find out a qualitative test for proteins, fats and oils, amino acids and test, any fruit juice, saliva, and urine for them.
Solution: Biuret test for protein : The biuret test is a chemical test used for determining the presence of peptide bonds. In a positive test, a copper II ion (Cu2+ ion) is reduced to copper I (Cu+) which forms a complex with the nitrogen and carbon of peptide bonds in an alkaline solution. A violet colour indicates the presence of proteins.
Ninhydrin test for amino acid: Ninhydrin (2,2 Dihydroxy indane-l,3-dione) is a chemical used to detect ammonia or primary and secondary amines. When reacting with these free amines, a deep blue or purple colour known as Ruhemann’s purple is evolved. Amino acid analysis of proteins is also done by ninhydrine. Most of the amino acids (including a-amino acids) are hydrolysed and reacted with ninhydrin except proline (a secondary amine). Amino acid containing a free amino group and a free carboxylic acid group reacts together with ninhydrin to produce coloured product. When the amino group is secondary, the condensation product is yellow.
NCERT Solutions For Class 11 Biology Biomolecules Q13
Solubility test for fats and oils : A positive solubility test for fats is that the fat dissolves in lighter fluid and not in water. In this test, 5 drops of fat or oil are added in two test tubes containing 10 drops of lighter fluid and 10 drops cold water respectively.
Fruit juice contains sugar so it cannot be tested by the above-mentioned tests. Saliva contains proteins, mineral salts, amylase etc., so it can be tested for protein and amino acids. Urine contains proteins, so it can be tested for it.

14. Find out how much cellulose is made by all the plants in the biosphere.
Solution: About 100 billion tonnes of cellulose is prepared per year by the plants of the world.

15. Describe the important properties of enzymes.
Solution: The important properties of enzymes are as follows:
(i) The enzymes are generally proteins which are high molecular weight complex globular proteins. They can associate with non-protein substance for their activity.
(ii) The enzymes do not start a chemical reaction but only accelerate it. They combine temporarily with the substrate molecules and are not consumed or changed permanently in the reaction which they catalyse.
(iii) The enzyme controlled reactions are reversible.
(iv) The enzymes are specific in action. An enzyme catalyses only a particular kind of reaction or acts on a particular substrate only.
(v) The enzymes are thermolabile i.e., heat sensitive and can function best at an optimum temperature. Similarly, enzymes show maximum activity at optimum pH.
(vi) The enzymes are inactivated by poisons and radiation.